Scientific studies have shown that shark attacks on humans have increased consistently over the last several decades (see FIGS. 1-2). This increase is directly correlated to the amount of time humans spend in the ocean. Since the 1990s, surfers have experienced the highest percentage of shark attacks.
Most shark attacks are believed to be cases of mistaken identity, where human beings are mistaken for seals, sea lions, sea turtles, and other natural prey of sharks. Sharks typically hunt for their prey by swimming along the ocean floor and looking for recognizable shapes at the surface of the water. From this position, a shark may mistakenly identify a surfer as a source of food, thus provoking an attack.
The fact that people are rarely eaten after being bitten by sharks supports the theory that sharks do not regard humans as food. Indeed, studies show that, in the majority of unprovoked shark attacks, the shark bites its victim, and then actually spits out the removed flesh. Some researchers in the field believe that sharks do not eat humans because human flesh is too boney and takes longer to digest than foods which form the staples of a shark's diet. This may, in turn, render the shark more lethargic and vulnerable to attack. By contrast, the flesh of seals, sea lions, and other natural prey of sharks has a high blubber content, which is easier for sharks to digest and which provides an energy-rich diet.
Shark attacks that occur on surfers are classified as “unprovoked” shark attacks, defined as incidents where an attack on a live human by a shark occurs in its natural habitat without human provocation of the shark. There are three major kinds of unprovoked shark attacks. By far the most common are “hit and run” attacks, which typically occur in the surf zone. Swimmers and surfers are the normal targets of such attacks. In “hit and run” attacks, the victim seldom sees its attacker, and the sharks do not return after inflicting a single bite or slash wound. In most instances, these attacks are believed to be cases of mistaken identity that occur under conditions of poor water visibility and a harsh physical environment (e.g., breaking surf and strong wash/current conditions).
The International Shark Attack File has officially documented unprovoked shark attacks since 1958. The number of unprovoked shark attacks has grown at a steady rate over the past century (see FIGS. 1-2). Overall, the 1990's had the highest attack total of any decade.
Many researchers in the field believe that the recent increase in the number of shark attacks is not the result of an increase in the aggressiveness of sharks towards humans, but arises instead from an increase in world population, coupled with a general increase in the amount of the time humans spend in the sea. Indeed, the number of shark-human interactions transpiring in a given year has been directly correlated to the amount of human time spent in the sea. As the world population continues to upsurge and the amount of time spent in aquatic recreation continues to rise, annual increases in the number of shark attacks on humans are expected to occur.
Referring again to FIGS. 1-2, the upward trend in shark attacks on humans is particularly troublesome for surfers, since surfers have experienced the highest percentage of unprovoked shark attacks in recent decades. This increase has been directly correlated to the increase in the popularity of the sport over this time period. The sharks that are most commonly involved in unprovoked attacks on surfers are the Great White Carcharodon carcharias, Tiger Galeocerdo cuvier, and the Bull shark Carcharhinus leucas. These sharks, known as the “Big Three” in the shark attack world, are large species capable of inflicting serious injuries to their victims, and are commonly found in areas where humans are in the water.